Volumetric display arrangement and a method for representing content of an image

ABSTRACT

Disclosed is volumetric display arrangement for representing content of an image at different focal distances in a view of real-world environment. The volumetric display arrangement includes at least one image projection unit operable to project multiple depth planes of the image, at least one electro-optical unit comprising two or more optical diffuser elements arranged parallel to each other, the at least one electro-optical unit being positioned to receive the projected multiple depth planes of the image thereon and configured to independently display one of the projected multiple depth planes of the image at one of the two or more optical diffuser elements at a given instant of time, and an optical combiner positioned with respect to the at least one electro-optical unit to combine the view of real-world environment with the independently displayed multiple depth planes of the image in the at least one electro-optical unit.

TECHNICAL FIELD

The present disclosure relates generally to display arrangements; andmore specifically to volumetric display arrangements for representing animage in a view of real-world environment. Furthermore, the presentdisclosure also relates to methods for representing an image in a viewof real-world environment.

BACKGROUND

With the advancements in technology, three-dimensional (3D) contentvisualization has gained popularity in the recent years as information,data, objects, models and so forth visualized in three-dimensional (3D)format are effectively perceived and retained by the human brain.Therefore, three-dimensional imagery is used in the fields of education(for example, to show three-dimensional models to students at schoolsand colleges), civil engineering, air traffic control management (forexample, to model airspace surrounding an airport), architecture,medicine, research and science, military and defence (for example, todepict topographical models of battlefields), and the like.

Several techniques have been developed to present three-dimensional (3D)imagery. Typically, two-dimensional displays such as Liquid CrystalDisplay (LCDs), diode-based displays and the like are employed topresent graphical content such as images, videos and so forth in athree-dimensional (3D) format. However, such techniques of representingthree-dimensional images on two-dimensional displays fail to presentphysical depth cues which are essential for a realistic representationof three-dimensional images and thus limiting the perception and spatialawareness of viewers viewing content on such displays. Furthermore, torealistically represent three-dimensional objects and scenes, modernthree-dimensional display technologies such as stereoscopic displays,including head-mounted displays, helmet-mounted displays and the likeare employed. However, such techniques are also associated with multipleproblems. Currently, techniques employing stereoscopic displays utilizeconventional 2D imaging solutions allowing presenting only psychologicaldepth cues and limited physical depth cues to imitate depth and thuscannot correctly drive accommodation and convergence. Thus, thesedepth-sensing mechanisms, which naturally are linked, become decoupled,which can cause unpleasant sensations to the viewer and thus limit theviewing time, and can also cause human errors based on inadequatedecision making due to incorrectly or imprecisely perceived 3Dinformation.

Therefore, in the light of the foregoing discussion, there exists a needto overcome the aforementioned drawbacks associated with conventionaltechniques employed for presenting three-dimensional imagery includingrepresentation of not just psychological depth cues but also correctphysical depth cues.

SUMMARY

The present disclosure seeks to provide a volumetric display arrangementfor representing a three-dimensional image in a view of a real-worldenvironment. The present disclosure also seeks to provide a method forrepresenting a three-dimensional image, via the volumetric displayarrangement in a view of a real-world environment. The presentdisclosure seeks to provide a solution to the existing problems such asimproper scalability, low resolution and representation ofthree-dimensional images within conventional display apparatuses forthree-dimensional imaging. An aim of the present disclosure is toprovide a solution that overcomes at least partially the problemsencountered in prior art, and offers a robust, user-friendly volumetricdisplay arrangement capable of enhanced representation ofthree-dimensional graphical information in terms of brightness,contrast, resolution and so forth.

In one aspect, an embodiment of the present disclosure provides avolumetric display arrangement for representing content of an image atdifferent focal distances in a view of real-world environment for eyesof a viewer, the volumetric display arrangement comprising:

at least one image projection unit operable to project multiple depthplanes of the image;

at least one electro-optical unit comprising two or more opticaldiffuser elements arranged parallel to each other, the at least oneelectro-optical unit being positioned to receive the projected multipledepth planes of the image thereon and configured to independentlydisplay one of the projected multiple depth planes of the image at oneof the two or more optical diffuser elements at a given instant of time;and

an optical combiner positioned with respect to the at least oneelectro-optical unit to combine the view of real-world environment withthe independently displayed multiple depth planes of the image in the atleast one electro-optical unit.

In another aspect, an embodiment of the present disclosure provides amethod for representing content of an image at different focal distancesin a view of real-world environment for eyes of a viewer using at leastone electro-optical unit comprising two or more optical diffuserelements arranged parallel to each other, the method comprising:

projecting multiple depth planes of the image;

displaying, independently, one of the projected multiple depth planes ofthe image at one of the two or more optical diffuser elements at a giveninstant of time; and

combining the view of real-world environment with the independentlydisplayed multiple depth planes of the image.

Embodiments of the present disclosure substantially eliminate or atleast partially address the aforementioned problems in the prior art,and enable truthful depiction of the three-dimensional image via thevolumetric display arrangement. Further, the representedthree-dimensional images have an enhanced psychological depth cues andphysical depth cues to correctly imitate depth associated with an imagebeing viewed by the viewer. Additionally, the experience of the vieweris further enhanced by combining the view of real-world environment tothe image being viewed.

Additional aspects, advantages, features and objects of the presentdisclosure would be made apparent from the drawings and the detaileddescription of the illustrative embodiments construed in conjunctionwith the appended claims that follow.

It will be appreciated that features of the present disclosure aresusceptible to being combined in various combinations without departingfrom the scope of the present disclosure as defined by the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The summary above, as well as the following detailed description ofillustrative embodiments, is better understood when read in conjunctionwith the appended drawings. For the purpose of illustrating the presentdisclosure, exemplary constructions of the disclosure are shown in thedrawings. However, the present disclosure is not limited to specificmethods and instrumentalities disclosed herein. Moreover, those in theart will understand that the drawings are not to scale. Whereverpossible, like elements have been indicated by identical numbers.

Embodiments of the present disclosure will now be described, by way ofexample only, with reference to the following diagrams wherein:

FIG. 1 is an illustration of a schematic representation of a volumetricdisplay arrangement for representing content of an image at differentfocal distances in a view of real-world environment for viewer, inaccordance with an embodiment of the present disclosure;

FIG. 2 is an illustration of a schematic representation of architectureof a volumetric display arrangement, in accordance with an embodiment ofthe present disclosure;

FIGS. 3A-3B and FIGS. 4-5 are illustrations of schematic representationsof volumetric display arrangements implemented as a wearable displaydevice, in accordance with various embodiments of the presentdisclosure;

FIGS. 6A-6B are illustrations of schematic representations of volumetricdisplay arrangements implemented as a desktop display, in accordancewith different embodiments of the present disclosure;

FIG. 7 is an illustration of a schematic representation of a volumetricdisplay arrangement implemented as a heads-up display in a vehicle, inaccordance with an embodiment of the present disclosure; and

FIG. 8 is an illustration of steps of a method for representing contentof an image at different focal distances in a view of real-worldenvironment for eyes of a viewer, in accordance with an embodiment ofthe present disclosure.

In the accompanying drawings, an underlined number is employed torepresent an item over which the underlined number is positioned or anitem to which the underlined number is adjacent. A non-underlined numberrelates to an item identified by a line linking the non-underlinednumber to the item. When a number is non-underlined and accompanied byan associated arrow, the non-underlined number is used to identify ageneral item at which the arrow is pointing.

DETAILED DESCRIPTION OF EMBODIMENTS

The following detailed description illustrates embodiments of thepresent disclosure and ways in which they can be implemented. Althoughsome modes of carrying out the present disclosure have been disclosed,those skilled in the art would recognize that other embodiments forcarrying out or practicing the present disclosure are also possible.

In one aspect, an embodiment of the present disclosure provides avolumetric display arrangement for representing content of an image atdifferent focal distances in a view of real-world environment for eyesof a viewer, the volumetric display arrangement comprising:

at least one image projection unit operable to project multiple depthplanes of the image;

at least one electro-optical unit comprising two or more opticaldiffuser elements arranged parallel to each other, the at least oneelectro-optical unit being positioned to receive the projected multipledepth planes of the image thereon and configured to independentlydisplay one of the projected multiple depth planes of the image at oneof the two or more optical diffuser elements at a given instant of time;and

an optical combiner positioned with respect to the at least oneelectro-optical unit to combine the view of real-world environment withthe independently displayed multiple depth planes of the image in the atleast one electro-optical unit.

In another aspect, an embodiment of the present disclosure provides amethod for representing content of an image at different focal distancesin a view of real-world environment for eyes of a viewer using at leastone electro-optical unit comprising two or more optical diffuserelements arranged parallel to each other, the method comprising:

projecting multiple depth planes of the image;

displaying, independently, one of the projected multiple depth planes ofthe image at one of the two or more optical diffuser elements at a giveninstant of time; and

combining the view of real-world environment with the independentlydisplayed multiple depth planes of the image.

Throughout the present disclosure, the term “volumetric displayarrangement” used herein relates to specialized equipment for presentingthe three-dimensional (3D) image to a viewer in a manner that thethree-dimensional image truthfully appears to have actual physicaldepth. In other words, the volumetric display arrangement is operable toact as a device for visually presenting the three-dimensional image in athree-dimensional space. The volumetric display arrangement comprises atleast one image projection unit operable to project multiple depthplanes of the image. The volumetric display arrangement also comprisesat least one electro-optical unit comprising two or more opticaldiffuser elements arranged parallel to each other. The configuration anddetails about the various components of the volumetric displayarrangement are described in the subsequent paragraphs.

Throughout the present disclosure, the term “image projection unit” usedherein relates to specialized equipment for projecting the plurality ofimage slices (portions) of the three-dimensional image upon theplurality of optical diffuser elements of the volumetric displayarrangement. Optionally, the image projection unit comprises a lightsource, a spatial light modulator, a processor and projection optics.More optionally, the image projection unit relates to an arrangement ofoptical components (for example, such as lenses, mirrors, prisms,apertures, and the like) that are configured to direct a modulated lightbeam towards the optical diffuser elements. Notably, the imageprojection unit allows for sharply focusing the plurality of imageslices upon the plurality of optical diffuser elements. The imageprojection unit provides a sufficient depth of field which encompasses aprojection volume. As a result, sufficiently sharp images are displayedon the plurality of optical diffuser elements. Furthermore, the imageprojection unit may include an aperture to adjust at least a depth offield and a brightness of the plurality of image slices.

Optionally, the image projection unit is implemented by way of activeoptical components which are electrically controllable to actively focusthe plurality of image slices upon their corresponding optical diffuserelements. Examples of such active optical components include, but arenot limited to, liquid crystal-based electroactive lenses andelectrostatically controllable membranes.

Optionally, a refresh rate of the image projection unit is based upon avolumetric refresh rate of the volumetric display arrangement and thenumber of the plurality of optical diffuser elements. The refresh rateof the image projection unit can be understood to be a rate at which theplurality of image slices are projected by the projector of the imageprojection unit. Throughout the present disclosure, the term “volumetricrefresh rate” relates to a rate at which a given plurality of imageslices pertaining to a single three-dimensional image are displayed, insome cases repeatedly, on the plurality of optical diffuser elements ofthe volumetric display arrangement.

Furthermore, the term “three-dimensional image” relates to a volumetricimage (namely, an image having a height, a width, and a depth in thethree-dimensional space). A given three-dimensional (3D) image could bea given volumetric image of at least one three-dimensional object (forexample, such as a statue, a vehicle, a weapon, a musical instrument, anabstract design, and the like), a three-dimensional scene (for example,such as a beach scene, a mountainous environment, an indoor environment,and the like), and so forth. Moreover, the term “three-dimensionalimage” also encompasses three-dimensional computer-generated surfaces.Furthermore, the term “three-dimensional image” also encompasses athree-dimensional point cloud.

Throughout the present disclosure, the term “image slice” relates to aportion (namely, a slice or a fragment) of the three-dimensional image.The three-dimensional image can be deconstructed (or decomposed) intomultiple image slices corresponding to multiple depths within thethree-dimensional image, by way of image processing algorithms. Herein,the three-dimensional image is a combination of the plurality of imageslices. It will be appreciated that when a given volumetric displayarrangement is implemented by way of multiple optical diffuser elements,different parts of the image slice are displayed on different opticaldiffuser elements.

The volumetric display arrangement of the present disclosure isimplemented for representing content of the image at different focaldistances in the view of real-world environment for eyes of the viewer.As discussed, the image projection unit, in the volumetric displayarrangement, is operable to project multiple depth planes of the image.Optionally, the image projection unit is communicatively coupled to aprocessor configured to segregate a three-dimensional image fed theretointo the plurality of image slices. Notably, the processor may be apersonal computer with dedicated graphics processing unit or aspecialized hardware, software and/or a firmware combination. Theprocessor can be understood to be a unit that performs processing tasksfor the volumetric display arrangement. A plurality of computationaltasks are conveyed for execution on the graphics processing unit byutilizing application programming interfaces (APIs), possibly in variouscombinations, for example, such as NVIDIA®, CUDA®, OpenCL®, DirectX®,OpenGL®, etc. The image projection unit is configured to project theprocessed content of the image, i.e. the multiple depth planes of theimage. Optionally, the image projection unit may be implemented as aplurality of communicatively coupled units, such that, for example, oneof the communicatively coupled unit is responsible for receiving animage data from an image source, whereas another one is responsible forthe direct control of the image projection unit and another onecoordinates synchronous operation of image projection unit and theelectro-optical unit. The content of the image is represented atdifferent focal distances with respect to the viewer, such as the viewerperceives a depth corresponding to the multiple depth planes of theimage.

Furthermore, the at least one electro-optical unit, in the volumetricdisplay arrangement, comprises two or more optical diffuser elementsarranged parallel to each other, such that the at least oneelectro-optical unit is positioned to receive the projected multipledepth planes of the image thereon and configured to independentlydisplay one of the projected multiple depth planes of the image at oneof the two or more optical diffuser elements at a given instant of time.In the present electro-optical unit, the two or more optical diffuserelements may be adhered together to form a single unit, or may bearranged in stack with gaps (such as an air gap) in between. At leasttwo optical diffuser elements are required in the electro-optical unitto provide a depth associated with the 3D image. The two or more opticaldiffuser elements independently display the projected multiple depthplanes of the image at the given instant of time. Herein, the giveninstant of time is dependent on the refresh rate of the image projectionunit.

Optionally, a thickness of the two or more optical diffuser elementslies within a range of 0.3 millimetres to 2 millimetres; andspecifically about 1.1 millimetres. In an example, the thickness of theat least one optical diffuser may be from 0.3, 0.4, 0.5, 0.6, 0.7, 0.8,0.9, 1.0, 1.1, 1.2 or 1.3 mm up to 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2,1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2 mm.

Further, optionally, a number of the plurality of optical diffuserelements within the volumetric display arrangement lies within a rangeof 2 to 50. As an example, the volumetric display arrangement maycomprise from 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,18, 19, 20, 21, 22, 23, 24, 25, 30, 35 or 40 up to, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 35, 40, 45or 50 optical diffuser elements. Alternatively, optionally, the numberof the plurality of optical diffuser elements within the volumetricdisplay arrangement is greater than 50. As an example, the volumetricdisplay arrangement may comprise 55, 60, 65, 70, 75, 80, 85, 90, 95 or100 optical diffuser elements.

Optionally, the three-dimensional image is processed to generate apredefined number of image slices (referred to as the multiple depthplanes of the image throughout the disclosure) corresponding thereto. Inan embodiment, the predefined number of image slices that are to begenerated upon processing of the three-dimensional image is equal to thenumber of the optical diffuser elements within the volumetric displayarrangement. In such a case, when the electro-optical unit in use, andone image slice is to be projected per optical diffuser element. Inanother embodiment, the predefined number of the plurality of imageslices generated upon processing of the three-dimensional image islesser than the number of the plurality of optical diffuser elementswithin the volumetric display arrangement. In such a case, there wouldexist at least one unused optical diffuser element, after all the imageslices are projected upon the plurality of other optical diffuserelements. As an example, the number of optical diffuser elements in thevolumetric display arrangement may be equal to 10. In such a case, thethree-dimensional image may be processed to generate 2, 3, 4, 5, 6, 7,8, 9 or 10 image slices.

Furthermore, optionally, the processor is configured to perform at leastone image processing operation whilst processing the three-dimensionalimage to generate the plurality of image slices. The at least one imageprocessing operation could relate to pre-processing operations as wellas post-processing operations. Examples of the at least one imageprocessing operation include, but are not limited to, lineartransformation (for example, such as translation, rotation and the like)of the three-dimensional image, cropping of the three-dimensional image,addition and/or removal of graphical information and/or pointerinformation to the plurality of image slices, colour adjustment of thethree-dimensional image, contrast adjustment of the three-dimensionalimage, inter-slice antialiasing for the three-dimensional image.

In an embodiment, each of the two or more optical diffuser elements isoperable to be switched between an optically transparent state and anoptically light diffusing state. Optionally, a given optical diffuserelement has at least two operational states, the at least twooperational states comprising at least the optically transparent stateand the optically light diffusing state. When the given optical diffuserelement is in the optically transparent state, light within the visiblespectrum of electromagnetic radiation substantially passes therethrough,and the image slice is not displayed at the given display element.However, when the given optical diffuser element is in the opticallylight diffusing state, a majority of light incident upon the givenoptical diffuser element is forward scattered and the image slice isdisplayed at the given optical diffuser element. Notably, only one ofthe at least two optical diffuser element will be in the optically lightdiffusing state at a given point of time, whereas the remaining opticaldiffuser element will be in the optically transparent state.

In an embodiment, the at least one electro-optical unit comprises atransitional medium layer arranged between each of the two or moreoptical diffuser elements thereof, wherein the transitional medium layerhas a refractive index equivalent to a refractive index of one or moreof substrates of the optical diffuser elements in contact therewith. Thetransitional medium layer is provided between each of the two or moreoptical diffuser elements, wherein the transitional medium layer istypically a thin layer. The refractive index of the transitional mediumlayer is equivalent to, or an average or median of, the refractiveindexes of the substrates of each of the two or more optical diffuserelements in contact therewith, in order to avoid any distortions in theincident light that are likely to occur at the boundaries of thetransitional medium layer and the corresponding optical diffuserelement. Therefore, in the present electro-optical unit, the opticaldiffuser elements provide uninhibited transmission of light between eachother without much reflections at the boundaries between thecorresponding optical diffuser elements due to index matching by thetransitional medium layer.

Optionally, the transitional medium layer comprises one or more of anoptically transparent viscous resin and an optically transparentadhesive to hold the adjacent optical diffuser elements together. In anexample, the transitional medium layer may be implemented in the form ofa lamination or a coating. In one or more examples, each of the two ormore optical diffuser elements and the transitional medium layertherebetween are pressed together to expel any possible air bubbles fromthe transitional medium layer.

In an embodiment, the volumetric display arrangement further comprises acontroller operatively coupled to the at least one image projection unitand the at least one electro-optical unit, and being operable to controlthe at least one image projection unit to project the depth planes ofthe image in a time-multiplexed manner substantially synchronously withthe optical state changes of the two or more optical diffuser elementssuch that a respective depth plane of the image is projected when anintended optical diffuser element is in the optically light diffusingstate. The term “controller” relates to specialized hardware, software,firmware, or a combination of these, that is configured to control theoperational states of the plurality of optical diffuser elements of thevolumetric display arrangement. Notably, the controller electricallycontrols the operational states of the plurality of display elements,based upon the plurality of image slices that are projected via theimage projection unit. The controller electrically controls theoperational states of the plurality of optical diffuser elements in amanner that, at any given time, only one optical diffuser elementwhereupon a given image slice is to be projected, is in the opticallylight diffusing state while remaining optical diffuser elements are inthe optically transparent state. Furthermore, the controller utilizes acontrol signal for managing operation of the optical diffuser elements.Optionally, the controller controls each of the at least two opticaldiffuser elements to be in the optically light diffusing state, in acyclic manner. In an embodiment, a progressive order of switching eachof the at least two optical diffuser elements to the optically lightdiffusing state, is from a nearest optical diffuser element to afarthest optical diffuser element with respect to the viewer. In anotherembodiment, the progressive order of switching the optical diffuserelements to the optically light diffusing state is from the farthestoptical diffuser element to the nearest optical diffuser element withrespect to the viewer. In yet another embodiment, an interlaced order isemployed for switching the optical diffuser elements to the opticallylight diffusing state. It will be appreciated that the controllercontrols the operational states of the optical diffuser elementssubstantially synchronously with the projection of the plurality ofimage slices upon the optical diffuser elements.

Optionally, the controller controls operation of the volumetric displayarrangement according to a master-slave configuration. In such a case,the controller comprises a plurality of driver logic blocks forsynchronizing operation of the image projection unit and the opticaldiffuser elements, the plurality of driver logic blocks being arrangedhierarchically in a manner that one driver logic block functions as a‘master’ whereas other driver logic block(s) functions as ‘slave(s)’.The ‘master’ provides a synchronization signal to the ‘slave(s)’ forimplementing such a synchronization operation.

In an example, the image projection unit may project three image slicesIS1, IS2 and IS3 of a given three-dimensional image that are to bedisplayed upon three optical diffuser elements DE1, DE2 and DE3respectively. In such a case, when the image slice IS1 is to bedisplayed upon the optical diffuser element DE1, the controller may beconfigured to switch the optical diffuser element DE1 to the opticallylight diffusing state while switching the remaining optical diffuserelements DE2 and DE3 to the optically transparent state. Similarly, whenthe image slice IS2 is to be displayed upon the optical diffuser elementDE2, the controller may be configured to switch the optical diffuserelement DE2 to the optically light diffusing state while switching theremaining optical diffuser elements DE1 and DE3 to the opticallytransparent state. Furthermore, when the image slice IS3 is to bedisplayed upon the optical diffuser element DE3, the controller may beconfigured to switch the optical diffuser element DE3 to the opticallylight diffusing state while switching the remaining optical diffuserelements DE1 and DE2 to the optically transparent state. The aforesaidswitching pattern may be repeated cyclically for multiple times within asingle second based on the required refresh rate.

In another example, the controller may be used for controlling theoperation of the electro-optical unit. One of the main utilizations ofsuch a controller is in selecting the number of the optical diffuserelements used for the display of the 3D image. In other words, theelectro-optical unit may comprise eight optical diffuser elements,however only four of the eight optical diffuser elements are switched bythe controller as required.

Alternatively, optionally, the controller may be substituted by a deviceemploying a firmware and/or a software and so forth. For example, thedevice may be used to disable or enable the selected optical diffuserelements. That is, one of the optical diffuser elements may be kept in apermanently optically transparent state, while displaying the 3D image.In one example, some of the optical diffuser elements may be kept in a,generally, permanent optically transparent state and the 3D image isdisplayed by cycling the remaining optical diffuser elements between theoptically light diffusing state and the optically transparent state, asrequired.

The given optical diffuser element can be understood to act as anelectrically controllable screen (i.e. controlled by the controller),which passes light through itself whilst operating in the opticallytransparent state and makes such light visible to the viewer whilstoperating in the optically light diffusing state. Therefore, inoperation, optical diffuser elements are rapidly and sequentiallyswitched between the at least two operational states to display theplurality of image slices. As a result, there is produced a visibleeffect of actual physical depth within the three-dimensional image.

Optionally, the volumetric refresh rate of the volumetric displayarrangement lies within 20 Hz to 120 Hz. When the given plurality ofimage slices pertaining to the single three-dimensional image aredisplayed once at the optical diffuser elements, the volumetric displayarrangement is said to have displayed one volume of the singlethree-dimensional image. Therefore, the volumetric refresh rate of thevolumetric display arrangement relates to a number of volumes that thevolumetric display arrangement can display in one second. It will beappreciated that a high volumetric refresh rate facilitates aflicker-less image viewing experience for the viewer. As an example, ifa given volumetric refresh rate of the volumetric display arrangement is30 Hz, the volumetric display arrangement can display 30 volumes of agiven three-dimensional image in one second. Optionally, the volumetricrefresh rate of the volumetric display arrangement ranges from 40 Hz to100 Hz. More optionally, the volumetric refresh rate of the volumetricdisplay arrangement is 50 Hz. The volumetric refresh rate of thevolumetric display arrangement may thus range for example from 40, 45,50, 55, 60, 65, 70, 75 or 80 Hz up to 50, 55, 60, 65, 70, 75, 80, 85,90, 95 or 100 Hz.

In an embodiment, the volumetric display arrangement may be implementedas one of an augmented reality device, a mixed reality device, aheads-up display and a desktop display device. In particular, thevolumetric display arrangement may be implemented for augmented realityexperience or mixed reality experience in the form of a heads-up displayor a desktop display. It will be appreciated that the electro-opticalunit of the volumetric display arrangement may be implemented in aVirtual Reality (VR) display device, such as a stereoscopic VR headsetor a head mounted display. A VR display primarily is intended for a 3Drepresentation of a virtual data (such as a 3D image).

Furthermore, the volumetric display arrangement comprises the opticalcombiner positioned with respect to the at least one electro-opticalunit to combine the view of real-world environment with theindependently displayed multiple depth planes of the image in the atleast one electro-optical unit. It will be appreciated that byincorporating the optical combiner, the volumetric display arrangementmay be implemented in augmented reality (AR) display devices and mixedreality (MR) display devices, wherein the display devices may be headmounted displays, heads up displays, desktop displays and so forth. TheAR display devices and the MR display devices are constructed to ensureoptical fusion (amalgamation) of the real-world environment and thevirtually or a digitally projected 3D image. Notably, the AR displaydevices and the MR display devices require a combination of the view ofreal-world environment with the independently displayed multiple depthplanes of the images, therefore, the optical combiner is positioned withrespect to the at least one electro-optical unit such that the viewer isable to view the combined view of the 3D image (as generated by the atleast one electro-optical unit) and the real-world environment throughthe optical combiner. To achieve this, the multiple depth planes of theimage in the at least one electro-optical unit are projected on theoptical combiner.

In an embodiment, the volumetric display arrangement further comprisesan imaging device configured to capture and project the view ofreal-world environment onto the optical combiner. The imaging device mayinclude at least one of a depth camera, an image registering device, adigital single lens reflex (DSLR) camera, a mirror less camera, andfurther projection optics. The imaging device is communicatively coupledand in sync with the image projection unit. The imaging device capturesthe view of real-world environment and projects the view on the opticalcombiner, such that the viewer is able to view the multiple depth planesof the image as well as the view of real-world environment combined onthe optical combiner. Such an amalgamation of the view of real-worldenvironment and the multiple depth planes of the image enables theviewer to perceive the 3D image in the virtual reality, the augmentedreality or the mixed reality (as configured). Optionally, the imagingdevice may be used for rendering an image such as for an amalgamation ofa real-world and a virtual world, thereby recreating an altered or amixed reality content. In another implementation, the image(s) from theimaging device is digitally combined with virtual image being projectedon the optical diffuser elements, either by directly projecting theimage from the imaging device to the optical diffuser elements or bydigital processing at the controller, to perceive the combined 3D imagein the virtual reality, the augmented reality or the mixed reality (asconfigured).

Optionally, at least one auxiliary device may be communicatively coupledto the image projection unit. The at least one auxiliary deviceincludes, but is not limited to, a switch, a sensor, a combination ofmultiple sensors, a combination of multiple switches and so forth.Notably, the at least one auxiliary device is used to configure, alteror complement the operation of the volumetric display arrangement.

In an embodiment, the optical combiner is implemented as at least one ofa partially-transparent mirror, a switchable glass, a prism, awaveguide, a holographic optical element, a lens and a diffractiongrating. The optical combiner may be the partially-transparent mirror sothat the viewer is able to observe the view of real-world environment(i.e. immediate surroundings) through the optical combiner, due to itstransparent nature. Further, the optical combiner provides that a partof the projected 3D image, form the electro-optical unit, is reflectedtowards the viewer, due to its reflective nature. Thus, the opticalcombiner ensures optical fusion of the actual reality and the projected3D image (i.e. the digitally processed or the virtual reality).Furthermore, the optical combiner may be the prism or a combination ofprisms, the waveguide, the holographic optical element, the lens or acombination thereof, the diffraction grating and so forth.

Optionally, the optical combiner implemented as the waveguide includesan in-coupling element and an out-coupling element. The light associatedwith the multiple depth planes of the image is projected (or guided) bythe waveguide through the in-coupling element, via total internalreflection phenomenon, and the light reaches the out-coupling element.Thereby, the viewer is able to observe the recreated 3D image via theout-coupling element.

Optionally, the waveguide may be a geometrical refractive typewaveguide. In such a waveguide, the in-coupling element may be anoptical element such as a prism. Moreover, the out-coupling element maybe a series of angled semi-transparent (such as wavelength-sensitive)mirrors and so forth.

More optionally, the waveguide may be a holographic type waveguide. Insuch a waveguide, the in-coupling element may be diffraction gratingspecifically tailored for the waveguide. Moreover, the out-couplingelement may be a diffractive (such as a holographic) grating.

In an embodiment, the volumetric display arrangement comprises a firstelectro-optical unit and a second electro-optical unit, wherein the atleast one image projection unit is operable to project a first set ofimages and a second set of images corresponding to the image onto thefirst electro-optical unit and the second electro-optical unitrespectively to provide a stereoscopic effect. The optical combinersimplemented as the waveguides are generally employed in the AR displaydevices associated with a stereoscopic display. The stereoscopic displayrequires two sets of images, each set projected on the firstelectro-optical unit and a second electro-optical unit. Furthermore, theimage projection unit is communicatively coupled to both the firstelectro-optical unit and a second electro-optical unit in order toproject the first set of images and the second set of images on therespective electro-optical unit.

In an embodiment, the optical combiner has one of a planar shape, acurved shape and a free-form shape. The optical combiner may have thecurved shape to provide an optical strength to the optical combiner.Optionally, the optical combiner may be a parabolic or sphericalstructure. Moreover, the optical combiner may be in any free-form shape,depending upon an application of the electro-optical unit.

In an embodiment, the volumetric display arrangement further comprisesat least one optical member arranged between the at least oneelectro-optical unit and the optical combiner, wherein the at least oneoptical member guides projections of the independently displayedmultiple depth planes of the image from the at least one electro-opticalunit onto the optical combiner. The at least one optical member arrangedbetween the at least one electro-optical unit and the optical combineris configured to guide the projections of the multiple depth planes ofthe image formed on the two or more optical diffuser elements, such theguided projections are viewed by the viewer through the opticalcombiner.

In an embodiment, the at least one optical member is a single lens, or acombination of lenses, a Fresnel lens, a prism, a holographical opticalelement and a metamaterial optical element. Optionally, the at least oneoptical member may be arranged parallel to the electro-optical unit. Theat least one optical member may be single optical lens configured toguide the projections towards the optical combiner. Moreover, theoptical member may be combination of one or more optical lensesconfigured to guide the projections. Furthermore, the at least oneoptical member may be the Fresnel lens, the prism, the holographicaloptical element and the metamaterial optical element or a combinationthereof. It will be appreciated that using of such optical members allowthe 3D image projections to have an enhanced brightness and contrast,when projected from the electro-optical unit to the optical combiner.

In another embodiment, the at least one optical member is a magnifyingoptical element. Optionally, the at least one optical member may beplaced at an angle with respect to the electro-optical unit. Forexample, the angle between the at least one optical member and theelectro-optical unit may be in a range of 30 degrees to 60 degrees.Preferably, the angle between the at least one optical member and theelectro-optical unit may be 45 degrees. The magnifying optical elementis configured to project the recreated 3D image from the at least oneoptical member towards the optical combiner. Optionally, the magnifyingoptical element may be either a single optical element or multipleoptical elements, wherein the multiple optical elements comprise atleast one of the optical lens, a flat mirror, a curved mirror, anaspherical mirror, a freeform mirror and so forth.

In yet another embodiment, the at least one optical member is asemi-transparent beam splitter. In this embodiment, the optical memberis preferably configured to guide the projections towards the opticalcombiner. Notably, the semi-transparent beam splitter splits theincident light in two directions. The semi-transparent beam splitterguides the projections towards the optical combiner. Optionally, thesemi-transparent beam splitter is a substantially flat optical member.More optionally, the semi-transparent beam splitter is a 50/50 beamsplitter, wherein the 50/50 beam splitter is configured to transmit 50%of the incident light and reflect 50% of the incident light. It will beappreciated that usage of such at least one optical member minimizes adistortion in the projected multiple depth planes of the image on theoptical combiner, if any.

In an embodiment, the volumetric display arrangement further comprisesan optical element arranged between the at least one image projectionunit and the at least one electro-optical unit, wherein the opticalelement is operable to allow projection of each of the multiple depthplanes of the image from the at least one image projection unit onto anintended optical diffuser element of the at least one electro-opticalunit. Optionally, the optical element may be curved in shape. Suchcurved optical element ensures a focused light from the image projectionunit onto the intended optical diffuser element. More optionally, theoptical elements may be parabolic shaped, spherical shaped, free formshaped and so forth. Notably, the shape of the optical element isdesigned to work in conjunction with a projection lens of the projectorof the image projection unit, thereby ensuring projection of a sharpimage on the electro-optical unit. Yet more optionally, the opticalelement may be flat shaped mirrors, waveguides and so forth.

In an implementation, the electro-optical unit of the volumetric displayarrangement is employed in drive assistance systems. Notably, somevehicles are equipped with the heads-up display (HUD) system, whereinthe HUD system provides an information to an automobile driver withoutrequiring to draw eyes away from the road on which the automobile isbeing driven. Moreover, a HUD system is also designed to overlay themultiple depth planes of the image on top of the view of real-worldenvironment. By implementing the HUD system, the real-world environmentwith respect to the automobile may supplemented with a projection of amap, highlights of various objects requiring caution (such aspedestrians, other automobiles, animals and so forth), driving speed ofthe automobile and so forth for driver assistance. The existing HUDsystems are based on representation of such graphical information in twodimensions (2D). In other words, the existing automobile HUD systemsrecreate a virtual screen (such as on the optical combiner) on which therelevant information is shown to the automobile driver. While for themost rudimentary information the 2D graphical information seemssufficient, but for an improved spatial awareness and versatility, true3D HUD systems are desired.

The present volumetric display arrangement utilizing two or more opticaldiffuser elements allows a projection of virtual depth planes atmultiple distances with respect to the automobile driver, thus adding athird dimension to the perceived imagery through the optical combiner.Notably, a number and a position of the virtual depth planes isdetermined by a design of the electro-optical unit. Optionally, thevirtual depth planes may be in a range of 2 to 25. For example, thevirtual depth planes may be in a range of from 2, 4, 6, 8, 10, 12, 14 or16 up to 6, 8, 10, 12, 14, 16. 18, 20, 22, 24 or 25. It will beappreciated that by providing virtual depth planes, such as four virtualdepth planes, results in improved spatial awareness of the automobiledriver. In such an implementation, the multiple depth planes of theimage are projected via the image projection unit. Furthermore, theoptical member is operable to project the multiple depth planes onto theoptical combiner. Optionally, the optical elements may be employed toaccommodate the desired optical design within a front panel of theautomobile. In an embodiment, a windshield of the automobile isimplemented as the optical combiner that combines the view of thereal-world environment with the multiple depth planes of the image.

Optionally, in order to provide an efficient attenuation of theprojected processed image and the real-world environment, the windshieldmay be implemented as the semi-transparent mirror, wherein thetransparency versus reflection is configured to follow a ratio 90%/10%,85%/15%, 80%/20%, 75%/25%, 70%/30% and so forth. More optionally, a part(or a segment) of the windshield may be treated by a film-like materialresulting in the semi-transparent mirror. Yet more optionally, thefilm-like material may be either electrically controllable to change theoptical properties upon application/removal of a voltage or a current.Moreover, the film-like material may be an optical material sensitive tothe intensity of the ambient light conditions (such as a type of passivephoto-chrome material). Furthermore, a part of the projected lightreflected from the optical combiner (i.e. the windshield) may beapproximated as a tilted flat mirror. The reflected light reaches theautomobile driver who observes the reflected light as perceived virtualdepth planes.

In another implementation, the electro-optical unit of the volumetricdisplay arrangement is employed in compact 3D display systems, such as adesktop display. Such a system is primarily intended for indoor use ineducational, scientific, professional, leisure context and so forth. Theimage projection unit in the compact 3D display systems is equipped witha wide-angle lens ensuring large image throw ratio. Optionally, theimage projection unit may be a digital micro mirror device, an LCoS(Liquid Crystal on Silicon) device, a transmissive LCD spatial lightmodulator, a solid-state micro-LED array and so forth. Notably,utilization of the wide-angle projection lens is of importance to ensurereduced size of the enclosure and thus, of the compact 3D displaysystems. The light from the image projection unit is projected towardsthe electro-optical unit. Alternatively, optionally, the optical pathfrom the projection unit to the electro-optical unit may incorporate theoptical element for focusing the light. Furthermore, the light from theelectro-optical unit through the optical member is guided towards theoptical combiner.

In an example, the optical combiner may be a highly reflective flatmirror which is fixed to a lid of the desktop display. Alternatively,the optical combiner may be a semi-transparent mirror. Utilization ofthe reflective flat mirror, as the optical combiner, can provide virtualreality experience; and that of the semi-transparent mirror, as theoptical combiner, can provide an augmented or mixed reality experienceto a viewer directly viewing the optical combiner. Optionally, theoptical combiner can be a holographical optical combiner. Moreoptionally, the optical combiner may be a curved mirror, such as aparabolic mirror. Yet more optionally, the optical combiner may be thefree form shaped mirror.

It is to be understood that the light from the optical combiner reachesa viewer, who perceives the image as multiple virtual depth planes,wherein the multiple virtual depth planes contains spatiallydifferentiated information, thereby causing a sensation of the depth ofthe image. In an alternate implementation of the compact 3D displaysystems, the optical elements are employed between the image projectionunit and the electro-optical unit, in order to focus the light from theimage projection unit to the electro-optical unit.

The present disclosure also relates to the method for representingcontent of an image at different focal distances in a view of real-worldenvironment for eyes of a viewer using at least one electro-optical unitcomprising two or more optical diffuser elements arranged parallel toeach other. The method comprises projecting multiple depth planes of theimage. The method further comprises displaying, independently, one ofthe projected multiple depth planes of the image at one of the two ormore optical diffuser elements at a given instant of time. The methodfurther comprises combining the view of real-world environment with theindependently displayed multiple depth planes of the image. Variousembodiments and variants disclosed above apply mutatis mutandis to themethod.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1 illustrated is a schematic representation of avolumetric display arrangement 100 for representing content of an imageat different focal distances in a view of real-world environment forviewer 102, in accordance with an embodiment of the present disclosure.As illustrated, the volumetric display arrangement 100 comprises atleast one image projection unit 104, at least one electro-optical unit106, and an optical combiner 108 operable to project multiple depthplanes of the image. Further, the at least one electro-optical unit 106comprises three optical diffuser elements 106A, 106B, and 106C arrangedparallel to each other. The at least one electro-optical unit 106 ispositioned to receive the projected multiple depth planes of the imagethereon and configured to independently display one of the projectedmultiple depth planes of the image at one of the two or more opticaldiffuser elements (such as, 106A, 106B, and 106C) at a given instant oftime. Further, the optical combiner 108 is positioned with respect tothe at least one electro-optical unit 106 to combine the view ofreal-world environment with the independently displayed multiple depthplanes of the image in the at least one electro-optical unit 106. Inparticular, the optical diffuser element 106A nearest to the viewer 102,displays information related to one or more dynamic status of a vehiclesuch as current speed, fuel meter and the like. Further, the opticaldiffuser element 106B, displays obstructions on the road such as a rock,other vehicles and so forth and generate a warning if safetyinstructions are violated. Further, the optical diffuser element 106Cdisplays navigation information such as a left turn or a right turndepicted as an arrow on the optical diffuser element 106C.

Referring to FIG. 2, illustrated is a schematic representation ofarchitecture of a volumetric display arrangement 200, in accordance withan embodiment of the present disclosure. As shown, an electro-opticalunit 202 operable to project multiple depth planes of three-dimensionalimage, is communicatively coupled to the controller 204 which controlsthe operational state of the electro-optical unit 202. Further, an imageprojection unit 206 is communicatively coupled to the controller 204.The image projection unit 206 is communicatively coupled to theprocessor 208 configured to segregate the three-dimensional image fedthereto into the plurality of image slices. Further, the imageprojection unit 206 is communicatively coupled to an imaging device 210,wherein the imaging device 210 is configured to capture the view ofreal-world environment

Referring to FIG. 3A, illustrated is a schematic representation of avolumetric display arrangement 300A to be implemented as a wearabledisplay device, such as a headset, in accordance with an embodiment ofthe present disclosure. The volumetric display arrangement 300Acomprises a planar optical combiner 302A. As shown, multiple depthplanes of a three-dimensional image 304A are projected onto anelectro-optical unit 306A. Further, the multiple depth planes of thethree-dimensional image 304A are reproduced by the electro-optical unit306A and the corresponding light emanating from the electro-optical unit306A is guided through an optical member 308A arranged between theelectro-optical unit 306A and the planar optical combiner 302A, to beprojected towards the planar optical combiner 302A. The planar opticalcombiner 302A reflects a part of the multiple depth planes of thethree-dimensional image 304A towards the viewer 310A. As shown, theviewer 310A looks through the planar optical combiner 302A to view theprojected three-dimensional image on the planar optical combiner 302Acombined with a view of the real-world environment from behind theoptical combiner 302A. Notably, the planar optical combiner 302A may besemi-transparent in nature enabling the viewer 310A to observe immediatesurroundings ensuring optical fusion of real-world environment anddigitally processed three-dimensional image 304A, to provide anaugmented or mixed reality experience to the viewer 310A.

Referring to FIG. 3B illustrated is a schematic representation of avolumetric display arrangement 300B to be implemented as a wearabledisplay device, such as a headset, in accordance with an embodiment ofthe present disclosure. The volumetric display arrangement 300Bcomprises a curved optical combiner 302B. As shown, multiple depthplanes of a three-dimensional image 304B are projected onto anelectro-optical unit 306B. Further, the multiple depth planes of thethree-dimensional image 304B are reproduced by the electro-optical unit306B and the corresponding light emanating from the electro-optical unit306B is to be projected towards the curved optical combiner 302B. It maybe appreciated that since the optical combiner 302B is curved, thereforethe volumetric display arrangement 300B may not require a focusing lensor the like (such as the optical member 308A of FIG. 3A). The curvedoptical combiner 302B reflects a part of the multiple depth planes ofthe three-dimensional image 304B towards the viewer 310B. As shown, theviewer 310B looks through the curved optical combiner 302B. Notably, thecurved optical combiner 302B is semi-transparent in nature enabling theviewer 310B to observe immediate surroundings ensuring optical fusion ofreal-world environment and multiple depth planes of thethree-dimensional image 304B, to provide an augmented or mixed realityexperience to the viewer 310B. Notably, the curved optical combiner 302Bhas an enhanced optical strength (as compared to the planar opticalcombiner 302A of the volumetric display arrangement 300A as shown inFIG. 3A), and is therefore capable of effectively reflecting themultiple depth planes of the three-dimensional image 304B towards theviewer 310B, to provide an augmented or mixed reality experience to theviewer 310B.

Referring to FIG. 4, illustrated is a schematic representation of avolumetric display arrangement 400 to be implemented as a wearabledisplay device, such as a headset, in accordance with another embodimentof the present disclosure. The volumetric display arrangement 400comprises a curved optical combiner 402 and an optical member 404.Herein, the optical member 404 is a semi-transparent mirror. As shown,the multiple depth planes of a three-dimensional image 406 are projectedonto an electro-optical unit 408. Further, the multiple depth planes ofthe three-dimensional image 406 are reproduced by the electro-opticalunit 408 and the corresponding light emanating from the electro-opticalunit 408 is projected onto the optical member 404, arranged at an angleof 45 degrees with respect to the normal of the electro-optical unit408. Further, the curved optical combiner 402 gathers the projectedthree-dimensional image reflected from the optical member 404 andreflects a part of the projected three-dimensional dimensional imagefocused towards the viewer 410 after combining the three-dimensionalimage with the real-world environment, ensuring minimal distortion ofthe real-world environment and the projected three-dimensional image, toprovide a distortion-free augmented or mixed reality experience to theviewer 410.

Referring to FIG. 5, illustrated is a schematic representation of avolumetric display arrangement 500 to be implemented as a wearabledisplay device, such as a headset, in accordance with an embodiment ofthe present disclosure. The volumetric display arrangement 500 comprisesan optical combiner which is implemented as a waveguide 502. As shown,the waveguide 502 includes an in-coupling element 502A and anout-coupling element 502B. Further, an electro-optical unit 504 isemployed to receive multiple depth planes of three-dimensional image506. Further, the multiple depth planes of the three-dimensional image506 are reproduced by the electro-optical unit 504 and the correspondinglight emanating from the electro-optical unit 504 is guided through anoptical member 508 arranged between the electro-optical unit 504 and thewaveguide 502. In particular, the light associated with the multipledepth planes of the three-dimensional image are projected (or guided) onthe waveguide 502 by the in-coupling element 502A, via total internalreflection, and the light reaches the out-coupling element 502B.Thereby, a viewer 510, looking towards the waveguide 502, specificallyat the out-coupling element 502B, is able to observe the recreatedthree-dimensional image via the out-coupling element 502B mixed withreal-world environment behind thereof.

Referring to FIG. 6A, illustrated is a schematic representation of avolumetric display arrangement 600A implemented as a desktop display(similar to a laptop device), in accordance with an embodiment of thepresent disclosure. As shown, an image projection unit 602 employed forprojecting multiple depth planes of a three-dimensional image, isarranged beneath a lid 610 of the desktop display. Further, the multipledepth planes from the image projection unit 602 are directed towards theelectro-optical unit 604, operable to receive the corresponding imagedepth planes from the image projection unit 602. Further, the multipledepth planes emanating from the electro-optical unit 604 are guided,through an optical member 606, towards an optical combiner 608. Notably,the optical combiner 608 is a flat mirror which is fixed to the lid 610of an enclosure 611 of the desktop display, wherein one end of the lid610 is pivotally coupled to the enclosure 611 of the desktop display, inthe volumetric display arrangement 600A, via a hinge mechanism 612. Inparticular, the optical combiner 608 is a semi-transparent mirrorproviding mixing of the multiple depth planes of the image withreal-world environment behind thereof, and thus providing augmentedreality experience to a viewer 614. In some examples, the opticalcombiner 608 would serve as a lid by itself. Herein, the multiple depthplanes from the optical combiner 608 reaches the viewer 614, whichperceives the three-dimensional image as multiple virtual focus planes616A, 616B, 616C, 616D, 616D, 616E, and 616F containing spatiallydifferentiated information, with respect to the real-world environment,thus causing a sensation of depth.

Referring to FIG. 6B, illustrated is a schematic representation of avolumetric display arrangement 600B implemented as a desktop display, inaccordance with an embodiment of the present disclosure. As shown, animage projection unit 602 employed for projecting multiple depth planesof a three-dimensional image, arranged beneath a lid 610 of the desktopdisplay. Further, the multiple depth planes from the image projectionunit 602 are directed towards the electro-optical unit 604, operable toreceive the corresponding image depth planes from the image projectionunit 602. Herein, the multiple depth planes from the image projectionunit 602 are directed towards the electro-optical unit 604 through theoptical elements 618 and 620, wherein the optical elements 618 and 620are arranged between the image projection unit 602 and theelectro-optical unit 604 in order to minimize the optical path betweenthe image projection unit 602 and the electro-optical unit 604, to makethe present desktop display system compact in size. Further, themultiple depth planes emanating from the electro-optical unit 604 areguided, through an optical member 606, towards an optical combiner 608.Notably, the optical combiner 608 is a flat mirror which is fixed to thelid 610 of an enclosure 611 of the desktop display, wherein one end ofthe lid 610 is pivotally coupled to the enclosure 611 of the desktopdisplay, in volumetric display arrangement 600, via a hinge mechanism612. In particular, the optical combiner 608 is a semi-transparentmirror providing mixing of the multiple depth planes of the image withreal-world environment behind thereof, and thus providing augmentedreality experience to a viewer 614. In some examples, the opticalcombiner 608 would serve as a lid by itself. Herein, the multiple depthplanes from the optical combiner 608 reaches the viewer 614, whichperceives the three-dimensional image as multiple virtual focus planes616A, 616B, 616C, 616D, 616D, 616E, and 616F containing spatiallydifferentiated information, with respect to the real-world environment,thus causing a sensation of depth.

Referring to FIG. 7, illustrated is a schematic representation of avolumetric display arrangement 700 implemented as a heads-up display (ora driver assistance system) in a vehicle 702, in accordance with anembodiment of the present disclosure. As shown, an image projection unit704 is employed for projecting multiple depth planes of athree-dimensional image. Further, the multiple depth planes from theimage projection unit 704 are directed towards the electro-optical unit706, arranged to receive the corresponding image depth planes from theimage projection unit 704. Further, the multiple depth planes emanatingfrom the electro-optical unit 706 are guided, through an optical member708, towards a windshield 710 of the vehicle 702, wherein the windshield710 serves as the optical combiner. Notably, the components, includingthe image projection unit 704, the electro-optical unit 706 and theoptical member 708, are arranged beneath a front panel 712 of thevehicle 702, such that the multiple depth planes emanating from theelectro-optical unit 706, and passing through the optical member 708arranged in the front panel 712, are guided towards the windshield 710.The multiple depth planes from the windshield 710 are reflectedtherefrom to reach a viewer 716, which perceives the three-dimensionalimage as multiple virtual focus planes 718A, 718B, and 718C containingspatially differentiated information thus causing a sensation of depth.In the present implementation, the virtual focus plane 718A nearest tothe viewer 716, displays information related to one or more dynamicstatus of the vehicle such as current speed, fuel meter and the like,the virtual focus plane 718B displays obstructions on the road such as arock, other vehicles and so forth and generate a warning if safetyinstructions are violated, and the virtual focus plane 718C displaysnavigation information such as a left turn or a right turn depicted asan arrow on the virtual focus plane 718C; thus providing the viewer 716with perception of the information being projection on the real-worldenvironment of a road in front thereof providing a mixed realityexperience. In some examples, the volumetric display arrangement 700comprises an imaging device 714 employed for registering the real-worldenvironment. Notably, the real-world three-dimensional images areexported to the image projection unit 704, wherein the three-dimensionalreal-world environment is combined with the multiple depth planesemanating from the electro-optical unit 706 to be projected on thewindshield 710 providing an augmented reality experience, e.g. forlearning driving in a simulator.

Referring to FIG. 8, illustrated are steps of a method 800 forrepresenting content of an image at different focal distances in a viewof real-world environment for eyes of a viewer using at least oneelectro-optical unit comprising two or more optical diffuser elementsarranged parallel to each other, in accordance with an embodiment of thepresent disclosure. At a step 802, multiple depth planes of the imageare projected. At a step 804, one of the projected multiple depth planesof the image is displayed independently at one of the two or moreoptical diffuser elements at a given instant of time. At a step 806, theview of real-world environment is combined with the independentlydisplayed multiple depth planes of the image.

Modifications to embodiments of the present disclosure described in theforegoing discussion are possible without departing from the scope ofthe present disclosure as defined by the accompanying claims.Expressions such as “including”, “comprising”, “incorporating”, “have”,“is” used to describe and claim the present disclosure are intended tobe construed in a non-exclusive manner, namely allowing for items,components or elements not explicitly described also to be present.Reference to the singular is also to be construed to relate to theplural.

1. A volumetric display arrangement for representing content of an imageat different focal distances in a view of real-world environment foreyes of a viewer, the volumetric display arrangement comprising: atleast one image projection unit operable to project multiple depthplanes of the image; at least one electro-optical unit comprising two ormore optical diffuser elements arranged parallel to each other, the atleast one electro-optical unit being positioned to receive the projectedmultiple depth planes of the image thereon and configured toindependently display one of the projected multiple depth planes of theimage at one of the two or more optical diffuser elements at a giveninstant of time; and an optical combiner positioned with respect to theat least one electro-optical unit to combine the view of real-worldenvironment with the independently displayed multiple depth planes ofthe image in the at least one electro-optical unit.
 2. A volumetricdisplay arrangement according to claim 1, wherein each of the two ormore optical diffuser elements is operable to be switched between anoptically transparent state and an optically light diffusing state.
 3. Avolumetric display arrangement according to claim 2, further comprisinga controller operatively coupled to the at least one image projectionunit and the at least one electro-optical unit, and being operable tocontrol the at least one image projection unit to project the depthplanes of the image in a time-multiplexed manner substantiallysynchronously with the optical state changes of the two or more opticaldiffuser elements such that a respective depth plane of the image isprojected when an intended optical diffuser element is in the opticallylight diffusing state.
 4. A volumetric display arrangement according toclaim 1, wherein the optical combiner is implemented as at least one ofa partially-transparent mirror, a switchable glass, a prism, awaveguide, a holographic optical element, a lens and a diffractiongrating.
 5. A volumetric display arrangement according to claim 1,wherein the optical combiner has one of a planar shape, a curved shapeand a free-form shape.
 6. A volumetric display arrangement according toclaim 1, further comprising at least one optical member arranged betweenthe at least one electro-optical unit and the optical combiner, whereinthe at least one optical member guides projections of the independentlydisplayed multiple depth planes of the image from the at least oneelectro-optical unit onto the optical combiner.
 7. A volumetric displayarrangement according to claim 6, wherein the at least one opticalmember is a magnifying optical element.
 8. A volumetric displayarrangement according to claim 6, wherein the at least one opticalmember is a single lens, or a combination of lenses, a Fresnel lens, aprism, a holographical optical element and a metamaterial opticalelement.
 9. A volumetric display arrangement according to claim 6,wherein the at least one optical member is a semi-transparent beamsplitter.
 10. A volumetric display arrangement according to claim 1,further comprising an optical element arranged between the at least oneimage projection unit and the at least one electro-optical unit, whereinthe element is operable to allow projection of each of the multipledepth planes of the image from the at least one image projection unitonto an intended optical diffuser element of the at least oneelectro-optical unit.
 11. A volumetric display arrangement according toclaim 1, further comprising an imaging device configured to capture andproject the view of real-world environment onto the optical combiner.12. A volumetric display arrangement according to claim 2, wherein theat least one electro-optical unit comprises a transitional medium layerarranged between each of the two or more optical diffuser elementsthereof, wherein the transitional medium layer has a refractive indexequivalent to a refractive index of one or more of substrates of theoptical diffuser elements in contact therewith.
 13. A volumetric displayarrangement according to claim 1 comprising a first electro-optical unitand a second electro-optical unit, wherein the at least one imageprojection unit is operable to project a first set of images and asecond set of images corresponding to the image onto the firstelectro-optical unit and the second electro-optical unit respectively toprovide a stereoscopic effect.
 14. A volumetric display arrangementaccording to claim 1 being implemented as one of an augmented realitydevice, a mixed reality device, a virtual reality device, a heads-updisplay and a table-top display device.
 15. A method for representingcontent of an image at different focal distances in a view of real-worldenvironment for eyes of a viewer using at least one electro-optical unitcomprising two or more optical diffuser elements arranged parallel toeach other, the method comprising: projecting multiple depth planes ofthe image; displaying, independently, one of the projected multipledepth planes of the image at one of the two or more optical diffuserelements at a given instant of time; and combining the view ofreal-world environment with the independently displayed multiple depthplanes of the image.